Cases will arise where the application does not comply with the EPC to such an extent that it is impossible to carry out a meaningful search into the state of the art on the basis of some of the subject-matter claimed (B‑VIII, 1, B-VIII, 2 and B-VIII, 3) and where the application also lacks unity of invention according to Art. 82 and Rule 44. It may be appropriate to raise only the issue of unity of invention and send an invitation under Rule 64(1) (see B‑VII, 1.1 and B-VII, 1.2), for example where a large number of claims which results in a severe lack of conciseness is resolved by splitting up the claims into the different inventions.
It may, however, be necessary to apply the procedures under both Rule 64(1) (invitation to pay additional search fees for inventions other than that first mentioned in the claims) and Rule 63(1). In this case, the EPO will first send the applicant an invitation according to Rule 63(1), requesting the applicant to indicate the subject-matter to be searched. In cases where the lack of unity is already apparent before any clarification is received from the applicant, this invitation would also identify the first invention mentioned in the claims (see F‑V, 4.4F‑V, 3.4) and the claims which relate to this invention, either in full or in part, and would invite the applicant to clarify what to search in respect of this invention first mentioned in the claims.
After expiry of the time limit according to Rule 63(1), the subject-matter, if any, to be searched in respect of the first invention will be determined according to the procedures specified in B‑VIII, 3.2. A partial search report (or exceptionally a declaration replacing it) will then be prepared on the invention first mentioned in the claims. This will be sent to the applicant along with an invitation to pay additional search fees under Rule 64(1) in respect of the other inventions. A provisional opinion on the patentability of the invention or unitary group of inventions first mentioned in the claims and the reasons for non-unity findings will also be provided. Where appropriate, the invitation under Rule 64(1) may also include an invitation according to Rule 63(1), inviting the applicant to clarify the subject-matter to be searched in respect of any additional inventions for which the applicant subsequently pays additional search fees.